/*
* Copyright (C) 1984-2007 Mark Nudelman
*
* You may distribute under the terms of either the GNU General Public
* License or the Less License, as specified in the README file.
*
* For more information about less, or for information on how to
* contact the author, see the README file.
*//*
* Primitives for displaying the file on the screen,
* scrolling either forward or backward.
*/
#include"less.h"
#include"position.h"
public int hit_eof; /* Keeps track of how many times we hit end of file */
public int screen_trashed;
public int squished;
public int no_back_scroll = 0;
public int forw_prompt;
public int display_next_file_or_exit = 0;
externint sigs;
externint top_scroll;
externint quiet;
externint sc_width, sc_height;
externint plusoption;
externint forw_scroll;
externint back_scroll;
externint ignore_eoi;
externint clear_bg;
externint final_attr;
externint oldbot;
externint unix2003_compat;
#ifTAGSexternchar *tagoption;
#endif/*
* Sound the bell to indicate user is trying to move past end of file.
*/staticvoideof_bell()
{
if (quiet == NOT_QUIET)
bell();
else
vbell();
}
/*
* Check to see if the end of file is currently "displayed".
*/staticvoideof_check()
{
POSITION pos;
if (ignore_eoi)
return;
if (ABORT_SIGS())
return;
/*
* If the bottom line is empty, we are at EOF.
* If the bottom line ends at the file length,
* we must be just at EOF.
*/
pos = position(BOTTOM_PLUS_ONE);
if (pos == NULL_POSITION || pos == ch_length())
hit_eof++;
}
/*
* If the screen is "squished", repaint it.
* "Squished" means the first displayed line is not at the top
* of the screen; this can happen when we display a short file
* for the first time.
*/
public voidsquish_check()
{
if (!squished)
return;
squished = 0;
repaint();
}
/*
* Display n lines, scrolling forward,
* starting at position pos in the input file.
* "force" means display the n lines even if we hit end of file.
* "only_last" means display only the last screenful if n > screen size.
* "nblank" is the number of blank lines to draw before the first
* real line. If nblank > 0, the pos must be NULL_POSITION.
* The first real line after the blanks will start at ch_zero().
*/
public voidforw(n, pos, force, only_last, nblank)
registerint n;
POSITION pos;
int force;
int only_last;
int nblank;
{
int eof = 0;
int nlines = 0;
int do_repaint;
staticint first_time = 1;
squish_check();
/*
* do_repaint tells us not to display anything till the end,
* then just repaint the entire screen.
* We repaint if we are supposed to display only the last
* screenful and the request is for more than a screenful.
* Also if the request exceeds the forward scroll limit
* (but not if the request is for exactly a screenful, since
* repainting itself involves scrolling forward a screenful).
*/
do_repaint = (only_last && n > sc_height-1) ||
(forw_scroll >= 0 && n > forw_scroll && n != sc_height-1);
if (!do_repaint)
{
if (top_scroll && n >= sc_height - 1 && pos != ch_length())
{
/*
* Start a new screen.
* {{ This is not really desirable if we happen
* to hit eof in the middle of this screen,
* but we don't yet know if that will happen. }}
*/
pos_clear();
add_forw_pos(pos);
force = 1;
if (!unix2003_compat) {
clear();
home();
}
}
if (pos != position(BOTTOM_PLUS_ONE) || empty_screen())
{
/*
* This is not contiguous with what is
* currently displayed. Clear the screen image
* (position table) and start a new screen.
*/
pos_clear();
add_forw_pos(pos);
force = 1;
if (top_scroll)
{
clear();
home();
} elseif (!first_time)
{
putstr("...skipping...\n");
}
}
}
while (--n >= 0)
{
/*
* Read the next line of input.
*/if (nblank > 0)
{
/*
* Still drawing blanks; don't get a line
* from the file yet.
* If this is the last blank line, get ready to
* read a line starting at ch_zero() next time.
*/if (--nblank == 0)
pos = ch_zero();
} else
{
/*
* Get the next line from the file.
*/
pos = forw_line(pos);
if (pos == NULL_POSITION)
{
/*
* End of file: stop here unless the top line
* is still empty, or "force" is true.
* Even if force is true, stop when the last
* line in the file reaches the top of screen.
*/
eof = 1;
if (!force && position(TOP) != NULL_POSITION)
break;
if (!empty_lines(0, 0) &&
!empty_lines(1, 1) &&
empty_lines(2, sc_height-1))
break;
}
}
/*
* Add the position of the next line to the position table.
* Display the current line on the screen.
*/
add_forw_pos(pos);
nlines++;
if (do_repaint)
continue;
/*
* If this is the first screen displayed and
* we hit an early EOF (i.e. before the requested
* number of lines), we "squish" the display down
* at the bottom of the screen.
* But don't do this if a + option or a -t option
* was given. These options can cause us to
* start the display after the beginning of the file,
* and it is not appropriate to squish in that case.
*/if (first_time && pos == NULL_POSITION && !top_scroll &&
#ifTAGS
tagoption == NULL &&
#endif
!plusoption)
{
squished = 1;
continue;
}
put_line();
#if 0
/* {{
* Can't call clear_eol here. The cursor might be at end of line
* on an ignaw terminal, so clear_eol would clear the last char
* of the current line instead of all of the next line.
* If we really need to do this on clear_bg terminals, we need
* to find a better way.
* }}
*/if (clear_bg && apply_at_specials(final_attr) != AT_NORMAL)
{
/*
* Writing the last character on the last line
* of the display may have scrolled the screen.
* If we were in standout mode, clear_bg terminals
* will fill the new line with the standout color.
* Now we're in normal mode again, so clear the line.
*/
clear_eol();
}
#endif
forw_prompt = 1;
}
if (ignore_eoi)
hit_eof = 0;
elseif (eof && !ABORT_SIGS())
hit_eof++;
else
eof_check();
if (nlines == 0)
eof_bell();
elseif (do_repaint)
repaint();
first_time = 0;
(void) currline(BOTTOM);
}
/*
* Display n lines, scrolling backward.
*/
public voidback(n, pos, force, only_last)
registerint n;
POSITION pos;
int force;
int only_last;
{
int nlines = 0;
int do_repaint;
squish_check();
do_repaint = (n > get_back_scroll() || (only_last && n > sc_height-1));
hit_eof = 0;
while (--n >= 0)
{
/*
* Get the previous line of input.
*/
pos = back_line(pos);
if (pos == NULL_POSITION)
{
/*
* Beginning of file: stop here unless "force" is true.
*/if (!force)
break;
}
/*
* Add the position of the previous line to the position table.
* Display the line on the screen.
*/
add_back_pos(pos);
nlines++;
if (!do_repaint)
{
home();
add_line();
put_line();
}
}
eof_check();
if (nlines == 0)
eof_bell();
elseif (do_repaint)
repaint();
elseif (!oldbot)
lower_left();
(void) currline(BOTTOM);
}
/*
* Display n more lines, forward.
* Start just after the line currently displayed at the bottom of the screen.
*/
public voidforward(n, force, only_last)
int n;
int force;
int only_last;
{
POSITION pos;
if (get_quit_at_eof() && hit_eof && !(ch_getflags() & CH_HELPFILE))
{
/*
* If the -e flag is set and we're trying to go
* forward from end-of-file, go on to the next file.
*/if (edit_next(1))
quit(QUIT_OK);
return;
}
pos = position(BOTTOM_PLUS_ONE);
if (pos == NULL_POSITION && (!force || empty_lines(2, sc_height-1)))
{
if (ignore_eoi)
{
/*
* ignore_eoi is to support A_F_FOREVER.
* Back up until there is a line at the bottom
* of the screen.
*/if (empty_screen())
pos = ch_zero();
else
{
do
{
back(1, position(TOP), 1, 0);
pos = position(BOTTOM_PLUS_ONE);
} while (pos == NULL_POSITION);
}
} else
{
eof_bell();
hit_eof++;
return;
}
}
forw(n, pos, force, only_last, 0);
}
/*
* Display n more lines, backward.
* Start just before the line currently displayed at the top of the screen.
*/
public voidbackward(n, force, only_last)
int n;
int force;
int only_last;
{
POSITION pos;
pos = position(TOP);
if (pos == NULL_POSITION && (!force || position(BOTTOM) == 0))
{
eof_bell();
return;
}
back(n, pos, force, only_last);
}
/*
* Get the backwards scroll limit.
* Must call this function instead of just using the value of
* back_scroll, because the default case depends on sc_height and
* top_scroll, as well as back_scroll.
*/
public intget_back_scroll()
{
if (no_back_scroll)
return (0);
if (back_scroll >= 0)
return (back_scroll);
if (top_scroll)
return (sc_height - 2);
return (10000); /* infinity */
}